Electrostatic-driven dopamine confined covalent organic frameworks membrane for enhancing hydrogen separation

Two-dimensional covalent organic frameworks (2D COFs) demonstrate significant potential for gas separation due to their crystalline nanochannels and structural tunability, yet practical implementation is constrained by inherent pore size limitations (>0.8 nm) and processing challenges. Herein, we engineered a Tp-PaSO₃H–COF-PDA composite membrane through an electrostatic-driven infusion of dopamine (DA) into solvothermally synthesized Tp-PaSO₃H–COF channels on α-Al₂O₃ supports. The resulting composite membranes own dual-function separation mechanisms. Pore size reduction enhances molecular sieving capabilities, resulting in an improvement in the separation performance of H₂/N₂ and H₂/CH₄. Concurrently, amino-rich polydopamine (PDA) networks provide specific CO₂ affinity sites that selectively hinder CO₂ transport, leading to further improved H₂/CO₂ separation performance. The membrane demonstrates operational stability under varying transmembrane pressures, feed compositions, temperatures, and extended operation. This confinement strategy transforms conventional covalent organic frameworks into precision separation platforms for sustainable hydrogen purification.